1. Field of the Invention
This invention relates to filtration units, and more particularly to a modular system easing the interchange of disposable filters in an air filtration unit.
2. Background of the Prior Art
Hospital administrators struggle with the creation of hospital infrastructure necessary to manage and contain infectious disease outbreaks. In the current infectious disease threat environment, occurrences of SARS, West Nile Virus, etc. have raised awareness of the need for infrastructure that can contain pathogens in an isolated environment so as not to risk infecting other patients or hospital workers attempting to treat an infected patient. Likewise, with increased threat of attacks using biological agents, hospitals need to be prepared to handle a potential outbreak of a contagious disease brought on by a biological attack. Most hospitals, however, lack appropriate isolation and filtration equipment to ensure a safe environment. The equipment that is available to provide clean, filtered air to what is intended to be a “clean” environment requires service, including replacement of filter members. Generally, such servicing requires breaking factory seals, and risks leaving gaps in what is intended to be the replacement sealing members that, in turn, could lead to an inadvertent spread of the pathogen that the filter assembly is intended to contain.
Likewise, in the current environment of heightened risk of terror attacks, emergency response personnel and administrations have realized that a very real need exists for providing methods and equipment to be able to respond to attacks involving chemical, biological, radiological, and/or nuclear weapons. In the event of such an attack, it is essential that emergency response personnel be able to establish a treatment center, a command center, and the like in what may be an environmentally hostile, and potentially lethal, environment. Of course, to do so, it is necessary that such personnel either be individually suited against the dangerous environment, or be located in a shelter that shields them from such environment. In the latter case, if the shelter must be located in a contaminated area but requires that persons spend extended amounts of time in the shelter, it is often impractical to supply each such person with their own self-contained air supply. Rather, as a practical matter, it would likely be necessary to filter air from outside of the shelter, and provide such filtered air to the closed environment inside of the shelter. Obviously, it is essential that the air be filtered to the greatest degree possible, as in the event of a biological attack, even minute amounts of contaminant making its way into the shelter could be deadly to the occupants.
Furthermore, in the event of such an attack, it may be necessary to establish an on-site isolation ward so that persons who are suspected of having been exposed to a dangerous contagion can be isolated from the general population, but may still be treated by emergency response personnel. In this case, it is necessary to ensure that any air escaping such shelter to the uncontaminated exterior is sufficiently filtered so as to ensure that such contaminants do not reach the general population.
Air filtration systems have been provided in the past that attempt to provide for filtration of particulate matter, bacteria, viruses, and the like. Such air filtration systems often take the form of a vertical steel cabinet having an air intake chamber at the bottom, one or more filters above the intake chamber through which the contaminated air is intended to pass, a motor-driven blower assembly above the filters, and a clean air discharge outlet. The types of filters provided are selected based on the environment in which the system is intended to be used. Notably, however, in highly toxic or dangerous environments, it would become necessary to change the filter after extended use. Unfortunately, changing the filter necessarily involves reseating a new filter against the appropriate sealing surfaces inside of the cabinet. While, during assembly in a controlled factory environment, a tight seal can be monitored and, through careful manufacturing procedures, can be created with relative confidence, replacing a filter assembly in a potentially hostile environment in the field does not provide such confidence. Notably, if an environment has been infected with a biological agent (which again may require very minute amounts of contagion to jeopardize the life of persons in the area), any leakage of air around the filter can be deadly. During the process of reseating a filter, a gap of only the size of a human hair can allow a sufficient number of partials of a biological contaminant into or out of the intended “clean” area that would jeopardize the health of the area's occupants. Thus, it is imperative that even in the field environment, the ability to establish a complete seal between the filter and its enclosure is maintained after a filter is replaced.
Moreover, filters and cabinet structures are typically certified by skilled technical personnel as having met a particular performance standard, i.e., as being capable of filtering particular pathogens at a given concentration over a given amount of time. While a filter may be tested at the manufacturing facility to confirm its ability to filter the intended contaminants, certification of the filter alone is meaningless if it is placed in a cabinet that allows flow of contaminated air around the filter. Likewise, certification of a cabinet without including the filter in the analysis is meaningless if gaps exist between the filter and housing that would allow contaminated air to pass. As there is currently no certification standard for the combined system of a cabinet with a filter in this area, there is urgent need to provide a combined filter and cabinet assembly that ensures a complete seal between the filter and cabinet even after a used or contaminated filter has been replaced in a hospital or in the field.
Additionally, the CDC requires monitoring the pressure in the room or shelter to which the filter is attached in order to maintain pressure in a specified band. Alarm and Warning set points allow visual and audible notification to the user when the pressure has deviated from the required operation window. Furthermore, data logging of the pressure, continuous or only on an alarm, can be used by risk management for a record of activity from the room or shelter.